A Brother's Duty
by Anath Tsurugi
Summary: Fili may be older, but Kili has always been bigger...and Fili has absolutely no problem with this. (Durincest)


(A/N) Second release of the day. This prompt asked for a size kink with Fili and Kili, with Fili absolutely loving that his little brother is bigger than he is (in every possible sense of the word), and Kili taking advantage of that.

Warnings: Durincest.

**A Brother's Duty**

The clang of swords echoed across the training grounds as Fili and Kili clashed. To anyone who didn't know them, the sparring match would have seemed violent and fiercely competitive, but those who did know the two brothers would have seen the fire of excitement in their eyes as their blades tangled over and over again. Thankfully, the sparring grounds were deserted this early morning, save for the two of them, as there was a bit more than the fire of competition in their excitement.

Kili was bigger and stronger than his older brother, but Fili often made up for that with his finesse with a blade, and today was no exception when he managed to knock his little brother's sword away.

"Do you yield, little brother?" Fili pressed, breathing hard, elation in his heart when he beheld the fiery look of defiance his brother fixed him with.

With a low growl, Kili dropped low and barreled forward, head butting his brother squarely in the gut and knocking him off his feet. Fili was so surprised by the move, he did nothing to block it, sword clattering away as he crashed to the ground. Before he could even draw another breath, Kili was on top of him, pinning him down with his greater weight. Kili leered down at him, taking in the heat in his brother's eyes with glee as he ground his hips subtly against his. Fili groaned quietly, his eyes briefly flickering shut.

"Do you yield…Fili?" the younger dwarf asked, his voice a hiss as he hovered just above his brother, lips mere inches from his, their hot breath mingling in that tiny space.

"_Ooh_…I yield, kha'I-ith. Now claim your victory," he urged, bucking his hips eagerly against Kili's. Kili grinned at him briefly before claiming his lips.

The pair moaned against each other as they writhed about on the ground, tasting and touching with wild abandon. It had been several days since they'd done this and the training had just been an excuse for all the others…an excuse to finally break the dam.

Their play on the floor was half coupling and half wrestling. At some point in the middle of things, they'd somehow managed to roll off to the side of the arena, coats and tunics torn away.

"Up…up against the wall," Kili panted as he reached to undo his brother's belt.

"Wait…" Fili groaned, reaching past Kili's hands to undo his belt first. "I want…to…let me see it first."

Again, Kili grinned at his older brother, enflamed by how eager he was. "As you wish…my king," he teased lightly as he moved to help Fili lower his trousers and small clothes, bringing his already straining cock into view. As with most things, Kili was the larger of the two, and Fili loved that about him. He absolutely loved it when Kili took him…when he thrust deep inside him, filling him with his enormous, dripping cock. In the light of day, he was Thorin's heir, the golden prince who would one day lead the clan of the Longbeards, but when it was just him and Kili, all by themselves with no witnesses, Fili loved to be utterly dominated by his baby brother.

Fili was already whimpering with want just from the _sight_ of Kili's prick, huge…swollen and red with desire, with a few drops of pre-cum leaking from the tip. Leaning forward, Fili gently began to squeeze him, causing Kili's head to fall back as he moaned in pleasure. Fili smiled, the scent of his little brother's arousal filling his nose with musk and spice.

"Mm…don't tease me too much…Nadadel. I'll come before I can _fuck_ you," he warned him.

"We can't have that," Fili said as he licked his lips. "Up against the wall, you said?" he asked, wriggling out from beneath his brother's larger body.

"Yes…right across from the doors," Kili said, retrieving a vial of oil from his discarded coat. "So if anyone comes in, they'll see us together. They'll see me…_fucking you._ They'll see me thrusting into your tight ass and they'll hear you scream my name and they'll _know_ who the future king of Durin's Folk belongs to," he said, his voice heated and passionate as he approached Fili, who was already leaning up against the wall, writhing and mewling, already helpless with desire.

"Oh…Mahal…yes…_yes,_" Fili panted, body already beginning to rut against the hard stone wall. When Kili suddenly seized him in his arms, Fili leaned back against him, whimpering as he slipped a hand between his legs and gently squeezed him through the cloth of his trousers.

"Mm…feel that…feel how hard you are…and that's all for me. Do you want me to fuck you, Fili?"

"Hngh…yes…kha'I-ith," he groaned, grinding himself against Kili's hand.

"_Little_ wolf?" Kili teased softly as he undid his belt, slipping a hand into his trousers, fondling the hot, engorged flesh. "You _still_ find that funny, don't you."

"Ah…yes…Brother. You will always be…my kha'I-ith. _Oh!_" he whimpered, panting a little bit harder as Kili stroked him. Faintly, he felt his lover's lips shift into a smile at the nape of his neck.

"And _you_…will always be my big brother."

"I love you," Fili whispered, fingers scrabbling against the stone as Kili pleasured him.

"And I love you…my king," Kili whispered back before slipping his hand out of Fili's clothes and taking a moment to push them down past his thighs. He knew Fili could hear it when he uncorked the vial.

"Hurry, Kili…hngh…hurry," he pleaded. He knew he wasn't going to last very long this time.

"Patience," the younger soothed, tracing a thick trail of oil around his hole. Then he began to push his fingers in.

"No!" Fili growled. "I want your cock. I want you in me _now._"

"Are you sure?" Kili asked, stepping back from the game a moment. "It _will_ hurt."

"I don't care. I can take it," he panted harshly. "Give it to me, Kili. Fuck me!"

Kili hesitated only a moment before slicking his prick very thoroughly. Then he positioned himself at his brother's entrance, tip only just touching the puckered hole.

"Are you ready for me, big brother?" Kili whispered in his ear.

"Yes…_oh_…I'm ready. _Take me,_" Fili urged, struggling not to thrust himself back on the cock that was about to impale him.

"As my king wishes," Kili said, slowly pushing just the head of his cock inside his brother's body.

Fili moaned aloud at the intrusion, feeling his body stretch deliciously to accommodate it. For several moments, the two of them held still, just getting used to the feeling. Then, very slowly, Kili started to push into him.

Fili groaned in both pleasure and pain with every inch. They had never done it so rough like this and he was _loving_ it, really _feeling_ the girth of his brother's huge cock. When Kili was fully buried inside him and they were slotted perfectly together, they took another moment to just _feel_ it.

"_Ooh_…Nadadith," Fili moaned in pleasure, legs trembling. "So…so _huge_…"

"Tell me, Fili," the younger urged, slipping his hand back between Fili's legs. "Tell me how you _want it._"

"Hngh…I…I want you to fuck me…_hard._ So hard. I want…to feel your strong body against me…and your large cock filling me…over and over again. Oh, Mahal, just _fuck me,_ Kili!" he begged, body beginning to move back against Kili's hips.

"I'm going to," Kili said with a smirk, giving an experimental twitch of his hips. Fili gave an obscenely loud moan at the simple movement, his body igniting with sensation.

Kili didn't hold back after that. He thrust in and out, again and again, taking Fili harder than he ever had before, and the heir to the throne was nearly screaming with bliss as he was pounded against the stone wall.

"_Mine!_" Kili snarled gleefully, one hand at Fili's cock and the other at his hip, fingernails digging until he'd drawn blood, never once letting up his pace. "All mine."

"Yes," Fili whimpered in pleasure, body moving in time with his brother's. "All yours…always. Oh, Mahal…oh, Kili…I…I'm going to-"

"Yes, _come,_" Kili hissed in his ear, jerking him harder. "Come for me, Azyungal."

"_Ah!_" Fili gave one last cry as he came, splattering sinfully against the stone. As his body seemed to melt with pleasure, he felt Kili come inside him, filling him with the hot, sticky burst of seed.

Still panting and breathing hard, both shaking with the force of the orgasm, the pair slowly dropped to their knees, still linked together. Fili leaned back against Kili, careful not to get his own cum on his face. After a time, the blond turned his head so that the two of them could share in a long, languid kiss.

"Thank you," he whispered against Kili's lips. "I _love_ it when you fuck me like that."

"Always happy to oblige," Kili said, still breathing hard, though his face was lit with a smile. "I know how rough it is to play the shining heir all the time."

"We should probably…continue elsewhere, though. Others will be wanting to use the grounds before long."

"Yes. I think we need a bath before we do anything else, though. Let's go down to the river," he said, slowly pulling out of Fili's body. The elder shivered in pleasure when he felt his brother's semen begin to dribble down his thighs. He was a little unsteady when Kili helped him to his feet, but still noticed the way he chuckled when he glanced back over his shoulder. "Heheh, should we maybe clean up before we leave?" he asked, nodding at the rather conspicuous splatter of sperm on the wall. Fili also laughed, but shook his head.

"No. Everyone knew we were coming here this morning. I _want_ them to see it. I want them to know what we did," he said, smirking deviously at his little brother, who smirked back. They briefly tousled each other's hair before going to retrieve the rest of their clothing, Fili undeniably walking a little funny.

They arrived at their favorite bathing spot not long after, a place where the river gathered in a pool that was concealed by several large boulders before flowing on its merry way. It was a good place to bathe…and for other things that didn't need to be seen. The two brothers stripped quickly, not wanting to take too long in the cold water. As they washed each other, Kili's hand trailed briefly over the injury he'd left on his brother's hip.

"Sorry about that," he said, gently running cold water over the red lines he'd drawn. It hadn't bled very much, but the scrapes still looked angry and raw. "Guess I got a little too excited."

"It's all right," Fili said, holding his hand in place over the broken skin. "I had fun, too. I wouldn't be much use to anyone if a little thing like this could take me down."

"We should probably get some salve for it when we head back."

Fili offered his brother another smirk, then drew his hand up to press a kiss to the knuckles. "Don't tell me you're ready to go back already. Aren't you up for a little adventure? We're out here in the middle of the forest…all alone. Who knows _what_ might happen," he said, moving his kisses around to the palm of his little brother's hand. Kili giggled, returning the smirk easily.

"What indeed. Ready for another round already? But I'm _so cold_, Nadad," he moaned, drawing Fili in closer, until the blond dwarf was kneeling right in front of him, legs spread wide to accommodate him. "I'm not sure if even _you_ could warm me up in this water."

"Challenge accepted," Fili said with a chuckle, leaning low over Kili's body and taking his flaccid cock in his hands. Kili's stones were just barely above the water.

Fili began by pressing several tiny kisses to the tip. When he felt his brother slowly start to react, he began to lick up and down the gradually hardening shaft.

"Hngh…come on, Fili. _Suck,_" the younger urged, pressing his hips up against his brother's body.

"Heh…thought I…wouldn't be able to get you up," Fili teased, his tongue circling the head of his cock.

"Well…now that you have…do you want my cock in you or not?" Kili teased, beginning to tangle his fingers in Fili's hair.

"Mm…in me," Fili groaned, licking at the drops of pre-cum. "_So far_ in me."

"Then take me in," Kili said, thrusting his hips up just slightly. Fili moaned as the head of his cock entered his mouth. He began to suck on the heated flesh like a dwarfling on a piece of rock candy. Kili joined in his sounds of pleasure at the feel of his brother's hot mouth, thighs already beginning to quiver.

Fili moved his mouth up and down, feeling himself grow hard as he watched his brother's cock disappear into his mouth over and over again. He could feel Kili's muscles twitching as he drew closer and closer to his climax. Repositioning himself just a little, he was able to take Kili all the way down his throat, easily tightening around the huge cock. He groaned in pleasure as he felt Kili begin to writhe against him.

Kili felt himself begin to shake as the hum of Fili's voice traveled through his body. As his fingers tightened their grip in Fili's hair, he began to push his mouth down on his cock even harder, and Fili moaned all the louder, loving every inch of large cock that penetrated him.

Kili finished with a very loud cry, slumping in the water as he released down his brother's throat. Fili made sure to swallow every drop before slowly pulling up from Kili's drained body.

"Tastes so good…just like always," Fili said, leaning over him once again, hands splayed out on either side of his head as he leaned down to kiss him. As they kissed, though, Kili reached up between his brother's legs, squeezing harshly. Fili gasped against his mouth.

"We're not quite finished here, are we," Kili said, jerking a little more roughly. "My dear brother hasn't come yet."

"Ha…nngh…Kili," he groaned. It took only a few more pulls for Fili to come into his brother's hand. He was left trembling over Kili's body, trying not to collapse on top of him. Faintly, he grinned down at him. "Heh…you little snake."

"What was that you said about little?" Kili asked, pulling his brother down to lie beside him, half in and half out of the water. "Do I need to show you how big I am again?"

"Of course you need to show me. You _always_ need to show me," Fili said, a faint trace of heat already smoldering in his eyes.

"Tonight, then," Kili said, leaning in to kiss him. "I'll need to eat before I can fuck you again. You're quite the workout, Urzudel."

"Trust me, Nadadith…so are you. I'll have to keep myself busy all day so I don't burst waiting for tonight."

"Heheh…that's the idea. To build the anticipation. It will make it that much sweeter," Kili said, cuddling close against Fili as the elder drew him in for more kissing.

XxX

Just as Fili had expected, the day was hideously long. After he and Kili returned to the mountains, it seemed that _everyone_ needed their help for something. Thorin and Dwalin needed him in the forge, Mother needed Kili in the kitchen, Gloin needed them in the stock rooms, Ori needed help in the archives. They barely even saw each other after parting ways at the settlement gates. Fili was ready to wring some necks by the time the evening meal was underway. Rather than wait around for the others to ask what his lousy attitude was about, Fili basically inhaled his food and left the hall, heading back to their shared chamber to wait for Kili.

"Thanks for leaving me to the wolves," Kili said when he finally arrived. He sounded peeved, but Fili could plainly see the grin on his face. "I had to field all the nagging from Thorin and Mother for your grumpy exit."

"Well, sorry, but I was going to kill the next person who asked me why I was angry, and it would have been most unfortunate if that person had been Ori. I will go on being grumpy until you fuck me at least once more."

"And here _I'm_ usually the catty one," Kili snarked as he removed his boots. "Well…I suppose I did promise…and I see you've eliminated a good portion of my work," he said, noting the fact that Fili was lying on their bed, already stripped of everything but his trousers.

"Got bored," Fili replied, twirling a braid around one finger. "You took your sweet time coming down from supper."

"Had to bring you this, didn't I," Kili said, carrying a small cloth pouch he'd brought to the bed. "You didn't stick around for dessert…and of _course_ Mother made your favorite tonight," he said, setting the pouch in Fili's lap. The blond dwarf reached inside and withdrew two strawberry cakes from inside. He considered the two pastries briefly, but ultimately fixed his brother with a bemused look.

"You want me to _eat_ right now? Are you serious?"

"Best eat them while they're fresh, Brother mine. You know that. Besides, you'll need something to do whilst I'm doctoring you," he said, reaching into the pouch and withdrawing the last item: a very small jar. When Fili said nothing, Kili offered the explanation, "Salve from Oin…for your hip?"

Fili gave him an odd smile. "Again…you want to do that _now?_"

"Oh, I can make it _very_ interesting. Trust me, Brother," Kili said, offering him a smile of his own. Finally giving in, Fili nodded and settled back on the bed, munching one of the strawberry cakes.

Kili began slowly, slipping off his trousers and small clothes. Then he gently massaged the injured hip, smoothing out the tension. Fili hissed in slight pain, but it was nothing he couldn't bear. He focused instead on the taste of strawberries in his mouth while Kili pressed several gentle kisses to his hip. Then he rubbed a small amount of the ointment into the skin. It stung at first, but then began to soothe…and as the rubbing gradually became more erotic, Fili began to moan, barely managing to finish the second cake.

"I want you on top this time," Kili said quietly, pulling Fili up into a kiss and tasting the strawberries on his lips. Fili grinned against him as the two switched places, Kili lying on the bed with Fili crouched over him. It took him only a moment to reach into their bedside table and withdraw their oil, offering it to his little brother with a wink.

Kili quickly uncorked the bottle and spilled a generous amount of the stuff onto his fingers, reaching between Fili's legs and beginning to rub it around and just inside his hole.

"I'm going to prepare you proper this time," Kili scolded mildly as he eased the tension from the tight ring of muscle. "I don't want to have to use that salve again so soon.

"Whatever you – want, Kili," he panted softly. "Just don't…don't be too long about it."

"Long, Brother?" Kili teased with a wink. Fili returned with a teasing scowl of his own.

"Well, if you're going to be like _that_,maybe I _won't_ let you prep me."

"Too late," he said as he pushed a finger inside him. Almost immediately, he had Fili moaning in pleasure, enjoying the feeling of penetration. Fili writhed above him, body beginning to rut as he worked a second finger in, gently pushing in and out and scissoring his fingers to open him up. After several minutes of this, Fili began to whimper.

"Come – come on, Kili. I'm ready. Please…please take me now," he urged, reaching a hand down to rub his brother's already hard cock.

"All right. Oil me up first," he said, passing Fili the bottle of oil as he withdrew his hand.

Even though he was eager, Fili was loving as he spread the oil over his brother's prick, quietly worshipping the large appendage with his fingers. He had never once begrudged his brother his larger size. He loved everything about Kili…and everything about his huge cock. He could hardly wait to have it filling his body once more. So once he had Kili completely slicked, he quickly set the bottle aside and positioned himself above his brother, head just at the entrance to his body.

"Ready?" Kili asked, eyes sparking with lust and adoration.

"_So_ ready," Fili breathed, gently beginning to slide down Kili's cock, relishing the feel of each inch as it slowly pushed into him.

They both moaned as one, quickly lost in the bliss of their coupling. It wasn't rough and hasty as it had been earlier, but slow and tender…loving…adoring…even though Fili was still enjoying being impaled on Kili's large cock and Kili was still enjoying penetrating him. That didn't mean these things always had to be violent. The pair moved slowly together on the bed, panting softly and groaning in quiet pleasure, making love to each other. When they came, it was nearly simultaneously, Fili bursting with a quiet gasp and spilling all over his brother's belly, and Kili releasing deep inside his brother, head falling back as he filled his lover with his seed.

When they'd finished, they collapsed quietly into each other's arms, bodies still joined and breathing heavily.

"I love you," Kili said as he tenderly kissed his lover's neck.

"I love you, too, Nadadith," Fili returned, smiling at him.

"I'll always be here for you…no matter what," he said, holding him close. "If they try to put too much on you, you just come to me. I'll give you what you need."

"Always," Fili said with a tiny laugh, cuddling close to his lover to sleep. Even though he was the older and it was supposed to be _he_ who protected Kili, they both knew that Kili was the one who protected him…who kept his spirit strong when the way became too difficult…and they would always reaffirm that truth when they came together in the dark beneath the mountains.

XxX


End file.
